1. Field of the Invention
The present invention relates to a transparent test strip system for determination by transmission photometry of one component of a liquid, in particular, a body fluid.
2. Background Information
The determination of one component in a liquid sample with the aid of test strips belongs to the established methods of diagnostic chemistry. In comparison with conventional wet chemical methods, such analyses are quicker and easier to carry out. In contrast, the accuracies customary in wet chemistry have as a rule not yet been reached with test strips. Many attempts have therefore been made to overcome these disadvantages (European Patent No. 0,064,710, DOS (German Published Specification) No. 3,130,749, DOS (German Published Specification) No. 2,332,760, DOS (German Published Specification) No. 2,532,918, DOS (German Published Specification) No. 2,602,975 and DOS (German Published Specification) No. 3,016,618). The structure of the carrier matrix and the evaluation method, in particular, play an important role in the context of these developments. The replacement of paper by synthetic polymers as the carrier material produced good progress here. With a suitable structural buildup, such systems are also suitable directly for application of whole blood. In the polymeric test strip systems for whole blood analysis known hitherto, the red blood cells are removed via microporous structural elements. On the other hand, the serum can penetrate into the reaction space of the matrix, where a specific color reaction occurs which, for example, can be evaluated after the red blood cells have been wiped off.
The structural build-up of such test elements, however, is as a rule relatively complicated, which also makes reproducible production difficult.
In addition to visual comparison, determination methods by reflectance photometry, in particular, have gained acceptance for evaluating the test strip reactions. However, such reflectometric determinations are based on physical approximation methods (Kubelka-Munk theory) and do not offer the precision of the transmission determination used in wet chemistry (Lambert-Beer Law).